1xx Series SIN (Atlantic and Ontario region)

Social Insurance Number applicants in Ontario might have noticed their SIN start with the number 1 series, which is the same as for people living in the Atlantic region. Social Insurance office started to roll out SIN that starts with 1 series for people who applied for their SIN in Ontario region in the fall 2021. This move seems to be because of the 4 and 5 series SIN has reached its limit.